Rotary radio antenna element



Sei@ 9, 143, R, A CQWDERY ET AL 2,255,446

ROTARY RADIO ANTENNA ELEMENT Filed SEPT.. 16, 1939 Patented Sept. 9,194i UNl'iE STTES EHC are

Robert Alan Gowdery, Geneva, and Howard L.

Jenkins, Springfield, Ohio, assignors to The American Fork a H oeCompany, Cleveland,

Ghio, a corporation of Ohio Application September 16, 1939, Serial No.295,260 Claims. (CL Z50- 33) Our invention relates to improvements inradio antennae and relates particularly to improvements in antennae forradio broadcasting purposes.

An object of our invention is to provide elements for use in radioantennae whether used for transmitting or receiving purposes.

Another object of our invention is to provide improved elements forradio antennae of the rotary beam type.

Another object ol our invention is to provide improved elements forradio antennae whereby such elements can more eliiciently transmitenergy.

Another object oi our invention is to provide improved elements forradio antennae which can be used in multiple form for use in thetransmission of what are commonly known as directive beams.

Another object oi our invention is to provide improved elements forradio antennae so constructed as not to be susceptible to swayresponsive to wind eiiects.

Another object of our invention is to provide an improved radio antennaelement in the form of a metallic rod which is adapted to behorizontally disposed, secured by one end only in straight form.

Another object of our invention is to provide improved elements forradio antennae of the type referred to wherein several elements may bemounted close together and whereby the supporting element may berelatively small in extent.

Another object of our invention is to provide an improved jointedelement for radio antennae.

Other objects of our invention and the invention itself will becomeapparent by reference to the attached drawing and the descriptionappended hereto.

In the drawing:

Fig. 1 is a View oi an assembled radio antenna comprising several of theelements of our invention;

Fig. 2 is invention;

Fig. 3 is a view of the element of Fig. 2 showing the amount of gravitysag which ordinarily would take effect and which has been predeterminedaccording to the specific dimensions of the element and the type ofmounting which will be employed;

Fig. 4 shows the element of Fig. 2 in its operative pre-bent relation;

Fig. 5 is a view oi a coupling for several spliced sections of theelement, and

a view of an antenna element oi our Fig. 6 is a view of several splicedsections of the element of Fig. 2 showing another embodiment of thecoupling.

It will be noted that certain dimensions are employed in connection withthe various figures of drawing and it is further to be noted that thesedimensions are optional but that they are used to show the relativeproportions of the element and the degree of pre-bending which isnecessary in order to take up any gravity sag which would occur in astraight tapered tube, such as is shown in the drawing.

The radio antenna of our invention is composed of several elements whichare preferably supported at one end. Since antenna elements are merelysupported at one end, a certain amount of dip or bend in a downwarddirection occurs in each element of my invention, whether it be composedof one or several component parts, which must be compensated for. Eachelement of our invention may be either a straight tube composed of oneor several partsor a tapered tube of any preferred degree of taper andcomposed of one or several parts.

In the drawing, We have shown in Figs. l, 2, 3 and 4 a tapered tubewhich is composed of three component parts, these parts beingdesignated, for the purposes of this description, as l, 2 and 3. In Fig.1, a pair of these are shown mounted in alignment on a support 8 havinginsulators 4, 5, 6 and 'l connecting the same with the elements. Inother Words, each element, whether it be the right hand elementdesignated as A, or the left hand element designated as B, are supportedby means of the support 8 and are mounted on a pair of insulators,whether it be the insulators 6 and l, or 4 and 5 extending upwardly fromthe support.

The elements are generally intended for use as directional antennaarrays and usually extend outwardly from the support a distance of 15 to18 feet although this is a matter of design and not essential. It is tobe noted that the present elements each have an overall length of 16'10" from the support end to the tip. Those portions of the antenna I and2, and l' and 2' which are closest to the mounting portion aresubstantially of equal length and the tip portions 3 and 3' are ofrelatively shorter length and considerably reduced diameter. Thereduction shown on Fig. 1 of the drawing herein for the entire givenlength of the tube of 16 10" is approximately .532 from the support endto the tip. The reduction, however, is gradual and is, in the formshown, preferably greater at the end of the first portion of the tubethan the end of the middle portion or in the last third of the tubelength.

It is to be noted in the form shown that the portion extending overapproximately the rst third of the total length of the tube shows noreduction in diameter; this is the portion of the element which issupported for a considerable extent by the main support by means of theinsulators. The tube is reduced prior to its point of juncture with thenext tube element, as shown in Fig. 2, however, and the reduced end ofthe second section is telescoped within the slightly larger diameter of`the end of the rst section, the end of the first tube section beingscrew threaded and adapted to have threaded engagement with a screwthreaded portion carried by the second section. The end tube section is,in turn, of still less diameter than the second section and is adaptedto have threaded engagement therewith in the manner shown in eitherFigs. or 6.

Obviously however, any desired wall thickness throughout `the length ofthe antenna element could b-e employed and any desired degree of taper.Further, the element could be of uniform outer diameter throughout witha uniform wall thickness. Our preferred embodiment, however, constitutesa sectional tapered tube of decreased wall thickness towards the tipportion the principal purpose of our invention being the prebending ofthe antenna element before it is adapted for use in its preferredmounting.

Fig. 4 of the drawing shows the amount of prebendinCr in a tube havingthe proportions shown in Fig. 2. This has been calculated in view of theamount oi drop or downward bend or sag which the element of Fig. 2assumes when the same is mounted, as shown in Fig. l, Fig. 3illustrating the amount of dip or bend which will occur in the elementdue to the force of gravity.

It is to be noted that in the practice of our invention we firstascertain the amount or" bend which will or may oc-cur and compensatefor the same by pre-bending the element in the propel'- tionate amountin the reverse direction.

In Fig. 4, for instance, this is shown as being an upward bend, thenwhen the element is mounted at one end with the bend upwardly of thetube, as in Fig. l, the element due to gravity will assume asubstantially horizontal position. It will be readily understood thatthe mounting structure can thence be comparatively short and the windresistance thus reduced.

It will also be readily understood that the transmission of energy willbe of increased eidciency. The principle of pre-bending the tube asdescribed herein may be applied to correct any other force beside-sgravity which might ordinarily be applied to the element when in use andwhich would tend to cause swinging such as wind pressure or the like.The elements of our invention may be either tubular or solid, tapered orstraight, and may be made of any kind of metal.

Although we have shown and described a preferred embodiment of ourinvention, we contemplate that numerous and extensive departures :may bemade therefrom without departing from the spirit of our invention andthe scope of the appended claims.

We claim:

l. An antenna element in the form of a rod adapted to be mounted solelyat one end thereof, said antenna being mounted in a horizon-tal positionand prior to mounting being prebent to compensate for a predetermineddownward droop when the element is in operative mounted horizontalposition whereby the element will assume a substantially straight formin the mounted p0- sition responsive to the eHect of gravity thereon.

2. A multiple beam antenna comprising a plurality of antenna elements,said elements each being in the form of a rod and adapted to be mountedsolely at one end thereof and to be disposed in substantial axialalignment with each other and in a generally horizontal position, saidelements prior to mounting being prebent to compensate for apredetermined downward droop when the element is in operative mountedhorizontally disposed position where-by the element will assume asubstantially straight form in the mounted position responsive to theeffect of gravity, said elements being maintained in substantiallyparallel relation to each other.

3. In combination, a sup-port, a pair of spaced insulators mounted uponsaid support and an antenna element having one end xedly mounted in saidinsulators, the other end being free, said antenna element being prebentto compensate for a predetermined downward bend when said antenna is inoperative mounted position, whereby said insulators may be mountedrelatively close together and said antenna element will assume asubstantially straight form in the mounted position responsive to theeiiect of gravity.

4. In combination, a support, a pair or' spaced insulators mounted uponsaid support and an antenna element having one end xedly mounted in saidinsulators, the other end being free, said antenna element being in theform of a rod, the portion which rests upon and between said supportsbeing of substantially uniform diameter and the remaining portion beingtapered to a relatively smaller diameter, the tapered portion of saidantenna prior to mounting being prebent to compensate for apredetermined downward bend when the antenna element is in operativemounted position, whereby the antenna will assume a substantiallystraight form in the mounted positicnresponsive to the effect ofgravity.

5. An antenna element in the form of a tubular rod comprising aplurality of Sections, said sections being threadedly secured togetherat their adjacent ends, whereby the length of said antenna element maybe'accurately adjusted laterally for different frequencies and saidantenna element being prebent in the shape of an arc to compensate for apredeternined downward bend of the antenna when the same is in operativemounted position, whereby the element will assume a substantiallystraight form in the mounted position responsive to the eiifect o1gravity.

ROBERT ALAN COWDERY. HOWARD L. J ENKINS.

